Zeolites are well known crystalline aluminosilicates. Zeolite molecular sieves are cheap, abundant and green materials which can be used as catalysts and/or ion exchangers. However, practical use can be problematic, because the small crystals sizes inhibit fluid transport. In order to overcome this problem, various approaches have been adopted. Attempts have been made to synthesise large crystals, but this involves the use of toxic chemicals, diffusion is compromised, and cracking of the zeolite crystals usually occurs on template removal. It is also known to pellet zeolites, but this increases production time and costs, and can interfere with adsorption. It is also known to grow zeolite films onto alumina, silica or metal substrates, but the dissolution of the substrate in the synthesising solution can lead to contamination or production problems and as metal substrates expand/contract on heating/cooling there is a risk of the zeolite film cracking and dislodging the zeolite crystals during utilization.